Trouble with background pictures in custom nav walker

I hav trouble with a custom nav walker. I want to output pictures a background on second level item. I get the pictures to show but some very weird url error that I can’t fix. the site is boardsupply.dk. Please help.

GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2015/12/wakeboarding-300×300.jpg%22 404 (Not Found)
longboard-hammond-organic-pintail-free-style-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-con…ploads/2015/11/longboard-hammond-organic-pintail-free-style-300×300.jpg%22 404 (Not Found)
large-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2015/11/large-300×300.jpg%22 404 (Not Found)
SUP-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2016/01/SUP-300×300.jpg%22 404 (Not Found)
surf-1-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2016/01/surf-1-300×300.jpg%22 404 (Not Found)
snowboard-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2015/12/snowboard-300×300.jpg%22 404 (Not Found)
snow_boots-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2015/12/snow_boots-300×300.jpg%22 404 (Not Found)
kitesurfing_alt-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2015/12/kitesurfing_alt-300×300.jpg%22 404 (Not Found)
Skateboards-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2016/01/Skateboards-300×300.jpg%22 404 (Not Found)
h%C3%B8retelefoner-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2016/01/h%C3%B8retelefoner-300×300.jpg%22 404 (Not Found)
snow_tilbehoer-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2016/01/snow_tilbehoer-300×300.jpg%22 404 (Not Found)
/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2016/01/shirts-300×300.jpg%22:1 GET https://boardsupply.dk/produkt-kategori/water/%22http:/boardsupply.dk/wp-content/uploads/2016/01/shirts-300×300.jpg%22 404 (Not Found)

Any suggestions?